Soft magnetic alloy thin film and plane-type magnetic device

ABSTRACT

A soft magnetic alloy thin film includes a fine crystalline phase and an amorphous phase. The fine crystalline phase includes an average crystalline grain size of 10 nm or less in diameter and has body-centered cubic structure mainly composed of Fe. The amorphous phase has a nitrogen (N) compound as the main composition and occupies at least 50% of the structure of the thin film. An element M is incorporated at least in the amorphous phase, and includes at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, W, and rare earth metal elements. A plane-type magnetic device is made using this thin film.

This application is a division of application Ser. No. 08/412,497, filedMar. 28, 1995 now U.S. Pat. No. 5,656,101.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to soft magnetic alloy thin films for usein, for example, thin-film inductors and transformers, and also tomagnetic devices incorporating the thin films.

2. Description of the Related Art

Soft magnetic alloys are used to produce, for example, magnetic headcores, thin-film inductors, transformers and choke coils. For thesedevices to operate adequately, the soft magnetic alloys must exhibitmagnetic properties such as high saturation magnetic flux density, highmagnetic permeability, low coercive force and the ability to be formedinto a thin film.

Various alloy compositions have been studied to identify alloys whichcan be used to produce suitable soft magnetic alloys. Conventionally,crystalline alloys such as Sendust (Fe-Al-Si alloy), permalloy (Fe-Nialloy), and silicon steel (Fe-Si alloy) have been employed as softmagnetic alloys. More recently, Fe-based and Co-based amorphous alloyshave also been used.

Although the conventional alloys are adequate for some applications, therecent trend toward smaller components and higher operating frequenciesnecessitates the development of new materials having even better softmagnetic properties for use as thin-film inductors, transformers, andchoke coils.

Although Sendust has adequate soft magnetic properties for someapplications, it is limited in that its saturation magnetic flux densityis about 1.1 tesla (T). Permalloy also can exhibit adequate softmagnetic properties, but is limited in that its saturation magnetic fluxdensity is as low as 0.8 T. Silicon steel has high saturation magneticflux density, but exhibit poor soft magnetic properties.

Another crystalline soft magnetic alloy thin film is disclosed in U.S.Pat. No. 5,117,321. This crystalline soft magnetic alloy comprises anFe-B-N system, where B represents at least one element selected from thegroup consisting of Zr, Hf, Ti, Nb, Ta, V, Mo, and W, and itscompositional ranges in atomic percent are 0<B<20 and 0<N<22, whereinwhen B≦7.5, then N>5, and when N≦5, then B>7.5.

The soft magnetic alloy thin film disclosed in U.S. Pat. No. 5,117,321is obtained by applying heat treatment after film formation to changethe amorphous phase to a crystalline phase. The resulting crystallinesoft magnetic alloy thin film has a high magnetic permeability at lowfrequencies (below 20 MHz), a high saturation magnetic flux density, andlow coercive force. The composition can be adjusted to eliminatemagnetostriction. However, the imaginary component of the magneticpermeability of this thin film becomes larger than the real component atfrequencies higher than about 20 MHz, as discussed below and shown inFIG. 16 of this application. When the imaginary component exceeds thereal component, the total magnetic permeability is substantiallyreduced. Therefore, the crystalline alloy disclosed in U.S. Pat. No.5,117,321 is inadequate for applications above 20 MHz.

On the other hand, Co-based amorphous alloys have adequate soft magneticproperties, but exhibit poor saturation magnetic flux density (1.0 T).Although Fe-based amorphous alloys have a saturation magnetic fluxdensity of 1.5 T or more, they also exhibit poor soft magneticproperties. In addition, Co-based and Fe-based amorphous alloys do nothave sufficient thermal-stability.

As described above, it has been difficult for conventional materials tohave both high saturation magnetic flux density and adequate softmagnetic properties for use in high frequency (i.e., above 20 MHz)applications.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a softmagnetic alloy thin film having a high saturation magnetic flux density,a low coercive force, and a high magnetic permeability, even at highfrequencies (i.e., above 20 MHz).

The foregoing object is achieved according to the present inventionthrough the provision of a soft magnetic alloy thin film including afine crystalline phase with an average crystalline grain size of 10 nmor less in diameter and having a body-centered cubic structurecomprising iron (Fe) as a main component; an amorphous phase comprisinga nitrogen (N) compound as the main component; and an element M includedat least in the amorphous phase, the element M including at least oneelement selected from the group consisting of Ti, Zr, Hf. V, Nb, Ta, Wand rare earth metal elements, wherein the amorphous phase occupies atleast 50% of the thin film structure.

The above-described soft magnetic alloy thin film according to thepresent invention has a compositional formula of Fe_(a) M_(b) N_(c),where the compositional ratios a, b, and c represent atomic percent inthe ranges of:

    60<a<80,

    7<b<26, and

    5<c<30.

In accordance with one embodiment of the present invention, thecompositional ratio c is preferably in the range of 10≦c≦22 atomicpercent, and even more preferably in the range of 10≦c≦18.

In accordance with another embodiment of the present invention, thecompositional ratio b is preferably in the range of 10≦b≦15 atomicpercent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the relationship between the flow ratio of N₂ gas and Argas in a film forming apparatus and the nitrogen content of a resultingsoft magnetic alloy thin film.

FIGS. 2(a)-(d) are charts illustrating the X-ray diffraction patterns ofnot-heat-treated (as deposited) samples having compositional formulas ofFe₇₆.2 Hf₁₃.3 N₁₀.5, Fe₇₂.2 Hf₁₃.2 N₁₄.6, Fe₆₁.2 Hf₁₂.5 N₂₆.3, andFe₅₇.9 Hf₁₂.6 N₂₉.5, respectively.

FIGS. 3(a)-(d) are charts illustrating the X-ray diffraction patterns ofsamples having the same compositional formulas as the samples of FIG. 2,and which has been annealed at 400° C. in a magnetic field of 2 kOe.

FIG. 4 is a triangular composition chart indicating the relationshipbetween the composition of an Fe-Hf-N system and its structure.

FIG. 5 is a triangular composition chart illustrating the relationshipbetween the composition of an Fe-Hf-N system and its resistivity.

FIG. 6 is a triangular composition chart showing the relationshipbetween the composition of an Fe-Hf-N system and its saturation magneticflux density.

FIG. 7B shows the relationship between nitrogen content and FIG. 7Ashows saturation magnetic flux density, and the relationship betweennitrogen content and resistivity of not-heat-treated samples having acompositional formula of Fe₇₇.6-61.5 Hf₁₃.6-13.2 N_(x).

FIG. 8 is a triangular composition chart showing the relationshipbetween the composition of an Fe-Hf-N system and its coercive force.

FIG. 9 is a triangular composition chart showing the relationshipbetween the composition of an Fe-Hf-N system and its magneticpermeability.

FIG. 10 is a triangular composition chart showing the relationshipbetween the composition of an Fe-Hf-N system and its magnetostrictioncoefficient.

FIG. 11C shows the relationship between nitrogen content and magneticpermeability, FIG. 11B shows relationship between nitrogen content andFIG. 11A shows magnetostriction, and the relationship between nitrogencontent and coercive force of not-heat-treated samples having acompositional formula of Fe₇₇.8-60.9 Hf₁₂.5-13.5 N_(x).

FIG. 12A shows a deposition condition of a crystalline structurecorresponding to each content of nitrogen as shown in FIGS. 12B, 12C and12D.

FIG. 12D shows the relationship between the nitrogen content andmagnetic permeability, FIG. 12C shows the relationship between nitrogencontent and magnetostriction, and FIG. 12B shows the relationshipbetween nitrogen content and coercive force, of samples having acomposition formula of Fe₇₇.8-60.9 Hf₁₁.1-13.5 N_(x).

FIG. 13 is a graph showing magnetic permeability as a function offrequency for a sample having a composition formula of Fe₇₂.2 Hf₁₃.2N₁₄.6 which has been annealed at 400° C. for 10.8×10³ seconds in amagnetic field of 2 kOe.

FIG. 14 is a graph showing magnetic permeability as a function offrequency for a sample having a composition formula of Fe₆₉.7 Hf₁₁.9N₁₈.4 which has been annealed at 400° C. for 10.8×10³ seconds in amagnetic field of 2 kOe.

FIG. 15 is a graph showing magnetic permeability as a function offrequency for a sample having a composition formula of Fe₆₅.1 Hf₁₁.1N₂₃.8 which has been annealed at 400° C. for 10.8×10³ seconds in amagnetic field of 2 kOe.

FIG. 16 is a graph showing magnetic permeability as a function offrequency for a soft magnetic alloy thin film having a compositionformula of Fe₈₂.6 Hf₇.7 N₉.7 which has been annealed at 550° C. for sixhours in a magnetic field of 1.1 kOe.

FIG. 17 is a graph showing magnetic permeability as a function offrequency for a soft magnetic alloy thin film having a compositionformula of Fe₇₇.8 Hf₁₃.1 N₉.1 which has been annealed at 400° C. for10.8×10³ seconds in a magnetic field of 2 kOe.

FIG. 18 is a graph showing magnetic permeability as a function offrequency for a soft magnetic alloy thin film having a compositionformula of Fe₆₉.5 Hf₁₂.2 N₁₈.3 which has been annealed at 400° C. for10.8×10³ seconds in a magnetic field of 2 kOe.

FIG. 19 is a graph showing magnetic permeability as a function offrequency for a soft magnetic alloy thin film having a compositionformula of Fe₆₀.9 Hf₁₃.5 N₂₅.6 which has been annealed at 400° C. for10.8×10³ seconds in a magnetic field of 2 kOe.

FIG. 20 is a graph showing magnetic permeability as a function offrequency for a soft magnetic alloy thin film having a compositionformula of Fe₇₇.8 Hf₁₃.1 N₉.1 which has been annealed at 500° C. for10.8×10³ seconds in a magnetic field of 2 kOe.

FIG. 21 is a graph showing magnetic permeability as a function offrequency for a soft magnetic alloy thin film having a compositionformula of Fe₆₉.5 Hf₁₂.2 N₁₈.3 which has been annealed at 500° C. for10.8×10³ seconds in a magnetic field of 2 kOe.

FIG. 22 is a graph showing magnetic permeability as a function offrequency for a soft magnetic alloy thin film having a compositionformula of Fe₆₀.9 Hf₁₃.5 N₂₅.6 which has been annealed at 500° C. for10.8×10³ seconds in a magnetic field of 2 kOe.

FIG. 23B shows the relationship between annealing temperature and FIG.23A shows resistivity, and the relationship between annealingtemperature and saturation magnetic flux density of three samples havingcompositional formulas of Fe₇₇.8 Hf₁₃.1 N₉.1, Fe₆₀.9 Hf₁₃.5 N₂₅.6, andFe₆₉.5 Hf₁₂.2 N₁₈.3, respectively.

FIG. 24D shows the relationship between annealing temperature andmagnetic permeability, FIG. 24C shows the relationship between annealingtemperature and magnetostriction, FIG. 24B shows the relationshipbetween annealing temperature and anisotropic magnetic field, and FIG.24A shows the relationship between annealing temperature and coerciveforce of samples having compositional formulas of Fe₇₇.8 Hf₁₃.1 N₉.1 andFe₆₉.5 Hf₁₂.2 N₁₈.3, respectively.

FIG. 25D shows the relationship between annealing temperature andmagnetic permeability, FIG. 25C shows the relationship between annealingtemperature and magnetostriction, FIG. 25B shows the relationshipbetween annealing temperature and anisotropic magnetic field, and FIG.25A shows the relationship between annealing temperature and coerciveforce of samples having compositional formulas of Fe₇₇.8 Hf₁₃.1 N₉.1 andFe₆₀.9 Hf₁₃.5 N₂₅.6, respectively.

FIG. 26 shows the X-ray diffraction patterns of samples havingcompositional formulas of Fe₇₇.8 Hf₁₃.1 N₉.1 and Fe₆₉.5 Hf₁₂.2 N₁₈.3,respectively.

FIG. 27 is a sketch showing a metal structure, magnified 3.2 milliontimes, of a sample having a compositional formula of Fe₇₂.2 Hf₁₃.2 N₁₄.6which has been annealed at 400° C. for 10.8×10³ seconds in a magneticfield of 2 kOe.

FIG. 28 is a sketch showing a metal structure, magnified 3.2 milliontimes, of a sample having a compositional formula of Fe₇₂.2 Hf₁₃.2 N₁₄.6which has been annealed at 900° C. for 10.8×10³ seconds in a magneticfield of 2 kOe.

FIG. 29 (a) is a plan view of a first example of a plane-type magneticdevice.

FIG. 29 (b) is a sectional view taken on line XXIX--XXIX of FIG. 29 (a).

FIG. 30 is a sectional view of a second example of a plane-type magneticdevice.

DETAILED DESCRIPTION OF THE INVENTION

A soft magnetic alloy thin film according to the present inventionincludes a soft magnetic alloy thin film including a fine crystallinephase with an average crystalline grain size of 10 nm or less indiameter and having a body-centered cubic structure comprising iron (Fe)as a main component; an amorphous phase comprising a nitrogen (N)compound as the main component; and an element M included at least inthe amorphous phase, the element M including at least one elementselected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, W and rareearth metal elements, wherein the amorphous phase occupies at least 50%of the thin film structure. The rare earth metal elements includeelements selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm,Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

Preferably, the soft magnetic alloy thin film has a composition formulaof Fe_(a) M_(b) N_(c), where the compositional ratios a, b, and c,represent atomic percentages in the ranges:

    60≦a≦80,

    7≦b≦26, and

    5≦c≦30.

The Fe content in the above-described composition formula should beequal to or greater than 60 atomic percent because, if the Fe content isless than 60 atomic percent, the saturation magnetic flux density of theresulting thin film becomes unacceptably small. Additionally, thecontent of element M should be equal to or greater than 7 atomic percentbecause, if the M content is less than 7 atomic percent, the resultingthin film does not include an amorphous structure. Further, the Ncontent should be greater than or equal to 5 atomic percent because, ifthe N content is less than 5 atomic percent, the resistivity andmagnetic permeability of the resulting thin film become unacceptablysmall.

To obtain high saturation magnetic flux density, the N content ispreferably 10 to 22 atomic percent, and even more preferably 10 to 18atomic percent. It is preferable the content of element M is 10 atomicpercent or more to ensure the formation of an amorphous alloy structure.To obtain superior soft magnetic properties, it is preferable that theupper limit of the content of element M is 26 atomic percent, and morepreferably 15 atomic percent.

It is preferable for the above-described soft magnetic alloy thin filmto include a structure which is at least 50% made up of an amorphousphase, with fine grains of a body-centered cubic Fe-based crystallinestructure, having an average crystalline size of 10 nm in diameter,dispersed in the amorphous phase along with nitrogen compounds includingelement M or Fe. As fine crystalline grains of Fe are formed in theamorphous phase, saturation magnetic flux density of the thin filmincreases. Because the structure is 50% or more made up of the amorphousphase, the resistivity of the soft magnetic alloy increased, therebyminimizing a loss of permeability at high-frequencies.

To manufacture a soft magnetic alloy thin film according to the presentinvention, for example, a thin film including an amorphous phase havingthe above-described compositional formula as its main component isformed on a substrate using a vapor-phase deposition method, such ashigh-frequency sputtering, wherein nitrogen gas is introduced. Thenitrogen content of the resulting soft magnetic alloy thin film can beadjusted by regulating the amount of nitrogen gas flowing in a filmforming chamber during vapor deposition. When the amount of nitrogen gassupplied to the film forming chamber is increased, the nitrogen contentof the deposited soft magnetic alloy thin film is also increased.

Fine crystalline grains may be formed in a soft magnetic alloy thinfilm, which is substantially made up of the amorphous phase, byannealing. When fine crystalline grains are formed by annealing, it ispreferable that the ratio of the crystalline phase to amorphous phase beless than 50%. If this ratio exceeds 50%, magnetic permeability of theresulting thin film at high-frequencies is decreased. The crystallinegrains dispersed in the amorphous structure are preferably 30 nm or lessin diameter, with the average diameter being 10 nm or less. These finecrystalline grains increase the saturation magnetic flux density of thethin film. The amorphous phase increases resistivity and preventsmagnetic permeability from decreasing at high-frequencies.

A soft magnetic alloy thin film according to the present invention maybe manufactured in the following manner.

Alloy targets having an average composition of Fe₈₇ Hf₁₃ were preparedand subjected to high-frequency sputtering at 200 W of power in an argoncarrier gas atmosphere containing 5% to 80% of nitrogen at a gaspressure of 0.6 Pa to produce soft magnetic alloy thin films of variouscompositions. The composition ratio of Fe and Hf was adjusted byincreasing or decreasing the amount of Hf chips in the alloy targets.The resultant thin films were annealed at 400° C. for three hours in amagnetic field of 2 kOe. Tables 1 and 2 show magnetic characteristics ofthe resultant thin films, including saturation magnetic flux density Bs(T); coercive force Hc (Oe); saturation magnetic field when a magneticfield is applied in the direction of the axis of difficult magnetization(hard axis) of the thin-film samples, namely the anisotropic magneticfield Hk (Oe); magnetic permeability μ (at 10 MHz), magnetostriction λs(×10⁻⁶); and resistivity ρ (μΩ cm). The saturation magnetic flux densityand the coercive force were measured using an A.C. BH tracer.Crystallized glass substrates having a film thickness of 1 to 2 μm wereemployed as the substrates.

                  TABLE 1    ______________________________________    SAMPLE                      Bs     Hc   Hk    No.                         (T)    (Oe) (Oe)    ______________________________________    1      Fe.sub.77.6 Hf.sub.13.6 N.sub.8.8                       AS DEPOSITED 0.62 1.68 3.52                       HEAT-TREATED 1.13 0.31 2.29    2      Fe.sub.71.5 Hf.sub.12.4 N.sub.16.1                       AS DEPOSITED 0.98 --   --                       HEAT-TREATED 1.19 --   4.24    3      Fe.sub.66.7 Hf.sub.11.8 N.sub.21.5                       AS DEPOSITED 0.65 --   0.8                       HEAT-TREATED 0.78 0.73 1.46    4      Fe.sub.74.3 Hf.sub.13.6 N.sub.12.1                       AS DEPOSITED 1.49 0.3  1.64                       HEAT-TREATED 1.5  0.4  2.64    5      Fe.sub.72.4 Hf.sub.12.3 N.sub.15.2                       AS DEPOSITED 1.38 0.43 2.04                       HEAT-TREATED 1.37 0.35 4.94    6      Fe.sub.69.1 Hf.sub.11.8 N.sub.19.1                       AS DEPOSITED 1.17 0.68 4.98                       HEAT-TREATED 1.16 0.78 6.70    7      Fe.sub.75.3 Hf.sub.14.7 N.sub.10                       AS DEPOSITED 0.38 --   --                       HEAT-TREATED 0.88 0.32 1.34    8      Fe.sub.64.8 Hf.sub.13.2 N.sub.22                       AS DEPOSITED 0.56 0.63 1.94                       HEAT-TREATED 0.68 0.37 2.32    9      Fe.sub.69.2 Hf.sub.13.9 N.sub.16.9                       AS DEPOSITED 0.90 0.21 0.66                       HEAT-TREATED 1.1  0.55 5.58    10     Fe.sub.67 Hf.sub.14 N.sub.19                       AS DEPOSITED 1.18 0.70 3.44                       HEAT-TREATED 1.17 0.66 5.68    11     Fe.sub.64.8 Hf.sub.14.1 N.sub.21.1                       AS DEPOSITED 0.52 0.31 0.58                       HEAT-TREATED 0.65 0.38 1.8    12     Fe.sub.61.5 Hf.sub.13.4 N.sub.25.1                       AS DEPOSITED      --   --                       HEAT-TREATED --   --   --    ______________________________________

                  TABLE 2    ______________________________________    SAMPLE    No.                 μ(10 MHz)                                  λs(× 10 - 6)                                          ρ(μΩ cm)    ______________________________________    1      AS DEPOSITED 38        0.93    193.6           HEAT-TREATED 2518      2.25    150.8    2      AS DEPOSITED 252       6.97    278.6           HEAT-TREATED 1174      8.62    251.9    3      AS DEPOSITED 253       4.06    312.7           HEAT-TREATED 1274      5.55    343.7    4      AS DEPOSITED 1192      3.76    140.9           HEAT-TREATED 4128      3.57    132.5    5      AS DEPOSITED 750       6.86    192.8           HEAT-TREATED 2114      7.00    186.5    6      AS DEPOSITED 734       10.02   293.3           HEAT-TREATED 1152      9.47    267.9    7      AS DEPOSITED 6.70      -0.06   235.0           HEAT-TREATED 948       1.36    184.4    8      AS DEPOSITED 352       7.83    263.3           HEAT-TREATED 1608      4.23    376.2    9      AS DEPOSITED 128       2.44    453.6           HEAT-TREATED 1522      7.77    291.4    10     AS DEPOSITED 343       8.83    292.0           HEAT-TREATED 1139      9.72    286.3    11     AS DEPOSITED 146       3.33    359.5           HEAT-TREATED 2067      3.81    385.8    12     AS DEPOSITED --        --      422.4           HEAT-TREATED --        --      376.9    ______________________________________

All the samples indicated in Tables 1 and 2 exhibited superiorsaturation magnetic flux density, coercive force, magnetic permeability,magnetostriction and resistivity. When the anisotropic magnetic field Hkof a sample is weak, the magnetic permeability of the sample was largeat low frequencies and drastically decreased at high frequencies. On theother hand, when the anisotropic magnetic field of a sample was strong,the magnetic permeability of the sample was relatively lower at lowfrequencies, but did not decrease significantly at high frequencies.This implies that the magnetic permeability of the thin film is superiorat high frequencies. Table 3 shows measured data of samples whichemployed elements other than Hf as the element M. It is understood fromTable 3 that the samples had good magnetic properties.

                  TABLE 3    ______________________________________                   Bs     Hc   μ    No.            (T)    (Oe) (10 MHz)                                      λs(× 10 - 6)                                              ρ(μΩ cm)    ______________________________________    13   Fe.sub.71 Ti.sub.14 N.sub.15                   1.2     2.03                               435    3.8     250    14   Fe.sub.68 Zr.sub.12 N.sub.20                   1.0     0.85                               2512   3.0     320    15   Fe.sub.75 V.sub.7 N.sub.18                   1.1     3.05                               538    2.8     150    16   Fe.sub.65 Nb.sub.18 N.sub.17                   1.0     1.12                               1895   4.0     280    17   Fe.sub.69 Ta.sub.10 N.sub.21                   1.2     0.68                               2020   3.2     353    18   Fe.sub.67 W.sub.10 N.sub.23                   0.9     3.55                               587    2.5     380    19   Fe.sub.64 Y.sub.26 N.sub.10                   1.0    0.9  1200   1.2     420    20   Fe.sub.72 La.sub.15 N.sub.13                   1.1    0.8  1582   3.2     183    21   Fe.sub.71 Ce.sub.14 N.sub.15                   1.0    1.3  1070   2.0     325    22   Fe.sub.70 Nd.sub.20 N.sub.10                   1.2    1.0  953    3.0     128    23   Fe.sub.68 Gd.sub.12 N.sub.20                   1.0    1.5  878    1.4     238    24   Fe.sub.68 Tb.sub.9 N.sub.23                   0.9    3.8  378    12.1    208    25   Fe.sub.70 Dy.sub.12 N.sub.18                   1.0    5.0  280    8.7     185    26   Fe.sub.73 Ho.sub.12 N.sub.15                   1.1    2.0  483    4.2     382    27   Fe.sub.75 Er.sub.12 N.sub.13                   1.2    3.3  380    2.8     383    ______________________________________

FIG. 1 shows the relationship between the nitrogen content of aresulting thin film and an N₂ /Ar flow rate ratio based on the amount ofnitrogen gas contained in argon gas flowing in the film forming chamberduring formation of the thin film.

As shown in FIG. 1, it is clear that increasing the amount of thenitrogen gas contained in the argon gas increases the nitrogen contentin the resulting thin film. It is also obvious that the nitrogen contentof the resulting thin film can be adjusted by altering the amount of thenitrogen gas contained in the argon gas.

FIGS. 2(a)-(d) shows X-ray diffraction patterns of not-heat-treated(i.e., as formed in the film forming chamber) samples havingcompositional formulas of Fe₇₆.2 Hf₁₃.3 N₁₀.5, Fe₇₂.2 Hf₁₃.2 N₁₄.6,Fe₆₁.2 Hf₁₂.5 N₂₆.3, and Fe₅₇.9 Hf₁₂.6 N₂₉.5.

As shown in FIGS. 2(a)-(d), these samples had broad peaks at diffractionangles ranging from 40 to 60 degrees, which is unique to an amorphousphase. Since the peaks corresponding to the compounds of Hf₄ N₃, Fe₄ N,Hf₄ N₃, and HfN were recognized in the figure, it was found that thestructure mainly comprised an amorphous phase made up of nitrogencompounds including Fe and Hf.

FIGS. 3 (a)-(d) illustrates X-ray diffraction patterns of the samplesshown in FIGS. 2 (a)-(d) after the samples were annealed at 400° C. in amagnetic field of 2 kOe. In FIGS. 3 (a)-(d), the annealing in themagnetic field is represented by letters, UFA, which stands for"uniaxial field annealing."

From FIGS. 3 (a)-(d), it is clear that the heat treatment did notsignificantly affect the X-ray diffraction patterns of the samples. Asunderstood from FIGS. 2 (a)-(d) and 3 (a)-(d), the thin film structureof the indicated samples exhibited a larger proportion of amorphousphase to crystalline phase as the nitrogen content.

FIG. 4 is a triangular composition chart indicating the relationshipbetween the composition and structure of not-heat-treated samples of theFe-Hf-N system.

In FIG. 4, the area indicated by "amo." is an amorphous phase, and anamorphous phase and crystalline phase are mixed in the area indicated by"amo.+bcc". In the composition range limited in the present invention,it was found that there existed two types of areas bordered by a dottedline. The symbol "a.d." in the figures indicates that a sample is notheat-treated (i.e., "as deposited").

FIG. 5 is a triangular composition chart illustrating the relationshipbetween the composition and resistivity (ρ) of not-heat-treated samplesof an Fe-Hf-N system. In FIG. 5, thick lines indicate resistivities of200, 300, and 400 μΩcm, respectively.

As clearly shown in FIG. 5, in the compositions according to the presentinvention, the resistivity increased as the Fe content became smallerand the N content became larger.

FIG. 6 is a triangular composition chart showing the relationshipbetween the composition and saturation magnetic flux density (Bs) ofnot-heat-treated samples of an Fe-Hf-N system. Thick lines indicatesaturation magnetic flux densities of 0.5 T, 1.0 T, and 1.5 T,respectively.

As clearly shown in FIG. 6, in the compositions according to the presentinvention, the saturation magnetic flux density increased as the Fecontent became larger and the N content became smaller.

FIG. 7B shows the relationship between the nitrogen content andsaturation magnetic flux density, and FIG. 7A shows the relationshipbetween the nitrogen content and resistivity, of not-heat-treatedsamples having a compositional formula of Fe₇₇.6-61.5 Hf₁₃.6-13.2 N_(x).

As clearly shown in FIGS. 7A-B, the following items were found in thespecified range of the Fe content. The nitrogen content be within therange of 5 atomic percent to 30 atomic percent in order to obtainsaturation magnetic flux density. The nitrogen content must be withinthe range of 10 atomic percent to 22 atomic percent in order to obtain asaturation magnetic flux density of 0.5 T or more. The nitrogen contentmust be within the range of 10 atomic percent to 18 atomic percent inorder to obtain a saturation magnetic flux density of 1.0 T or more.

FIG. 8 is a triangular composition chart showing the relationshipbetween the composition and coercive force of not-heat-treated samplesof an Fe-Hf-N system. In FIG. 8, thick lines indicate coercive forces of0.25 Oe, 0.375 Oe, 0.625 Oe, and 1.25 Oe, respectively.

As clearly shown in FIG. 8, it was found that, in the composition systemof the present invention, the coercive force was lower as the contentsof the three elements were restricted to amounts indicated at the centerof the boxed area according to the present invention.

FIG. 9 is a triangular composition chart showing the relationshipbetween the composition and magnetic permeability μ (10 MHz) ofnot-heat-treated samples of an Fe-Hf-N system. In FIG. 9, thick linesindicate magnetic permeabilities of 200, 500, and 1,000, respectively.

As clearly shown in FIG. 9, it is obvious that, in the compositionsystem of the present invention, higher magnetic permeability can beobtained as the Fe content is increased and the N content is decreased.

FIG. 10 is a triangular composition chart showing the relationshipbetween the composition and magnetostriction (λs) of not-heat-treatedsamples of an Fe-Hf-N system. In FIG. 10, thick lines indicate bordersof magnetostrictions of 0, 2×10⁻⁶, 5×10⁻⁶, and 10×10⁻⁶.

As clearly shown in FIG. 10, it was found that, in the compositionsystem of the present invention, the magnetostriction decreased as theHf content increased and the Fe content decreased, and there existed anarea where the magnetostriction was 0. Therefore, it is obvious thatcontrolling the amount of Hf and Fe easily adjusts the magnetostriction,and the magnetostriction can be set to 0.

FIG. 11C shows the relationship between the nitrogen content andmagnetic permeability μ (at 10 MHz), FIG. 11B shows the relationshipbetween the nitrogen content and magnetostriction (λs), and FIG. 11Ashows the relationship between the nitrogen content and coercive force(Hc), of not-heat-treated samples having a compositional formula ofFe₇₇.8-60.9 Hf₁₂.5-13.5 N_(x).

FIGS. 11A-C clearly show that the magnetic permeability achieves a peakvalue at a nitrogen content of about 15 atomic percent, and decreased asthe nitrogen content became greater or less than about 15 atomicpercent. It also clearly shows that the magnetostriction achieves a peakvalue at a nitrogen content of about 21 to 23 atomic percent, anddecreased as the nitrogen content became greater or less than thisamount. FIGS. 11A-C also show that the coercive force was lowest at anitrogen content of 14 to 24 atomic percent, and increased as thenitrogen content becomes larger than 24 atomic percent or smaller than14 atomic percent.

FIG. 12D shows the relationship between the nitrogen content andmagnetic permeability μ (at 10 MHz), FIG. 12C shows the relationshipbetween the nitrogen content and magnetostriction (λs), and FIG. 12Bshows the relationship between the nitrogen content and coercive force(Hc) of samples having a compositional formula of Fe₇₇.8-60.9Hf₁₁.1-13.5 N_(x). Data of samples not heat-treated (as deposited) wascompared with that of samples annealed at 400° C. for 10.8×10³ secondsin a magnetic field.

As clearly shown in FIGS. 12A-D, the magnetostriction and coercive forcedid not change substantially when the samples were annealed, but themagnetic permeability increased considerably. It is expected that amagnetic permeability of 1,000 or more can be obtained in thin filmswherein the N content range is 5 atomic percent to 30 atomic percent. Itis further expected that a magnetic permeability of 1,500 or more can beobtained in thin films wherein the N content range is 10 atomic percentto 30 atomic percent.

FIG. 13 is a graph showing the magnetic permeability of a sample havinga composition formula of Fe₇₂.2 Hf₁₃.2 N₁₄.6 which was annealed at 400°C. for 10.8×10³ seconds in a magnetic field of 2 kOe.

In general, magnetic permeability μ is denoted as:

    μ=μ'-iμ"

where μ' represents the real component of the magnetic permeability andμ" represents the imaginary (complex) component of the magneticpermeability. Magnetic permeability μ can also be represented asfollows:

    |μ|=(μ'.sup.2 +μ".sup.2).sup.0.5.

Generally, imaginary component μ" can be ignored at low frequenciesbecause it is insignificant, but it tends to become large at highfrequencies, and therefore cannot be ignored.

However, the magnetic permeability of the sample according to thepresent invention shown in FIG. 13 exhibited an imaginary component μ"which was smaller than the real component μ' even at frequencies higherthan 50 MHz, and μ did not decrease significantly. This indicates thatthe sample can be used at frequencies of as high as 100 MHz. The samplealso exhibited a saturation magnetic flux density of 1.5 T, a coerciveforce of 28 A/m (=0.35 Oe), an anisotropic magnetic field of 211 A/m(=2.64 Oe), and a resistivity of 1.3 μΩm, these being superior softmagnetic properties.

FIG. 14 is a graph showing the magnetic permeability of a sample havinga composition formula of Fe₆₉.7 Hf₁₁.9 N₁₈.4 which was annealed at 400°C. for 10.8×10³ seconds in a magnetic field of 2 kOe.

It was found that this sample exhibited imaginary component μ" which wassmaller than that of the sample shown in FIG. 13 at high frequencies,and it can be satisfactorily used at frequencies up to 100 MHz. Thissample also exhibited a saturation magnetic flux density of 1.4 T, acoercive force of 40 A/m (=0.5 Oe), an anisotropic magnetic field of 395A/m (=4.94 Oe), and a resistivity of 1.9 μΩm, these being superiormagnetic properties.

FIG. 15 is a graph showing of the magnetic permeability of a samplehaving a composition formula of Fe₆₅.1 Hf₁₁.1 N₂₃.8 which was annealedat 400° C. for 10.8×10³ seconds in a magnetic field of 2 kOe.

It was found that this sample exhibited an imaginary component μ" whichwas even smaller than that of the sample shown in FIG. 14 at highfrequencies, and it can be satisfactorily used at frequencies up to 100MHz. This sample also exhibited a saturation magnetic flux density of1.2 T, a coercive force of 63 A/m (=0.788 Oe), an anisotropic magneticfield of 536 A/m (=6.7 Oe), and a resistivity of 270 μΩcm, these beingsuperior magnetic properties.

FIG. 16 is a graph showing the magnetic-permeability frequencycharacteristics of a sample of a soft magnetic alloy thin film having acomposition formula of Fe₈₂.6 Hf₇.7 N₉.7 which was annealed at 550° C.for six hours in a magnetic field of 1.1 kOe. The crystalline softmagnetic alloy thin film produced by this process is disclosed in thespecification of U.S. Pat. No. 5,117,321 (discussed above). When heattreatment is applied for a long period at a high temperature as thatused for the measurement in FIG. 16, the whole structure becomescrystalline. The properties of the sample in this example are describedin U.S. Pat. No. 5,117,321. As described above, the sample is inferiorto the thin film produced in accordance with the present invention dueto a large loss in magnetic permeability at frequencies higher than 20MHz because the imaginary component μ" of the magnetic permeability islarger than the real component μ' at frequencies above 20 MHz.

In contrast with the above-described thin film, the soft magnetic alloythin film according to the present invention which mainly comprisesamorphous phases can have a low imaginary component of the magneticpermeability low even at high frequencies between 50 to 100 MHz, asshown in FIGS. 13, 14, and 15.

FIG. 17 is a graph showing measurement results of themagnetic-permeability frequency characteristics of a sample of a softmagnetic alloy thin film having a composition formula of Fe₇₇.8 Hf₁₃.1N₉.1 which was annealed at 400° C. for 10.8×10³ seconds in a magneticfield of 2 kOe.

It was found that this sample exhibited an imaginary component μ' whichwas sufficiently small at frequencies below 100 MHz, and became largerthan the real component μ' around 100 MHz. The sample is thereforesatisfactory for use at frequencies up to 100 MHz. This sample alsoexhibited a saturation magnetic flux density of 1.0 T, a coercive forceof 76.8 A/m (=0.96 Oe), an anisotropic magnetic field of 153.6 A/m(=1.92 Oe), a magnetostriction of 1.56×10⁻⁶, and a resistivity of 148μΩcm, these being superior magnetic properties.

FIG. 18 is a graph showing the magnetic-permeability frequencycharacteristics of a sample of a soft magnetic alloy thin film having acomposition formula of Fe₆₉.5 Hf₁₂.2 N₁₈.3 which was annealed at 400° C.for 10.8×10³ seconds in a magnetic field of 2 kOe.

It was found that this sample exhibited an imaginary component μ" whichwas sufficiently small at frequencies below 200 MHz, and became largerthan the real component μ' around 200 MHz. The sample can besatisfactorily used at frequencies up to about 200 MHz. This sample alsohad a saturation magnetic flux density of 1.4 T, a coercive force of59.2 A/m (=0.74 Oe), an anisotropic magnetic field of 308 A/m (=3.85Oe), a magnetostriction of 8.16×10⁻⁶, and a resistivity of 204 μΩcm,these being superior magnetic properties.

FIG. 19 is a graph showing the magnetic-permeability frequencycharacteristics of a sample of a soft magnetic alloy thin film having acomposition formula of Fe₆₀.9 Hf₁₃.5 N₂₅.6 which was annealed at 400° C.for 10.8×10³ seconds in a magnetic field of 2 kOe.

It was found that this sample exhibited an imaginary component μ" whichwas sufficiently small at frequencies below 100 MHz, and became largerthan the real component μ' between 100 MHz and 200 MHz. The sample canbe satisfactorily used at frequencies between 100 MHz and 200 MHz. Thissample also exhibited a saturation magnetic flux density of 1.1 T, acoercive force of 35.2 A/m (=0.44 Oe), an anisotropic magnetic field of210 A/m (=2.62 Oe), a magnetostriction of 6.5×10⁻⁶, and a resistivity of270 μΩcm, these being superior magnetic properties.

FIG. 20 is a graph showing the magnetic-permeability frequencycharacteristics of a sample of a soft magnetic alloy thin film having acomposition formula of Fe₇₇.8 Hf₁₃.1 N₉.1 which was annealed at 500° C.for 10.8×10³ seconds in a magnetic field of 2 kOe.

It was found that this sample exhibited an imaginary component μ" whichwas sufficiently small at frequencies below 80 MHz, and became largerthan the real component μ' around 80 MHz. The sample can besatisfactorily used at frequencies up to 80 MHz. This sample alsoexhibited a saturation magnetic flux density of 1.3 T, a coercive forceof 24 A/m (=0.3 Oe), an anisotropic magnetic field of 134.6 A/m (=1.82Oe), a magnetostriction of 1.65×10⁻⁶, and a resistivity of 131 μΩcm,these being superior magnetic properties.

FIG. 21 is a graph showing the magnetic-permeability frequencycharacteristics of a sample of a soft magnetic alloy thin film having acomposition formula of Fe₆₉.5 Hf₁₂.2 N₁₈.3 which was annealed at 500° C.for 10.8×10³ seconds in a magnetic field of 2 KOe.

It was found that this sample exhibited an imaginary component μ" whichwas sufficiently small at frequencies below 200 MHz, and became largerthan the real component μ' around 200 MHz. The sample can besatisfactorily used at frequencies up to about 200 MHz. This sample alsoexhibited a saturation magnetic flux density of 1.5 T, a coercive forceof 59.2 A/m (=0.74 Oe), an anisotropic magnetic field of 507.2 A/m(=6.34 Oe), a magnetostriction of 8×10⁻⁶, and a resistivity of 193 μΩcm,these being superior magnetic properties.

FIG. 22 is a graph showing the magnetic-permeability frequencycharacteristics of a sample of a soft magnetic alloy thin film having acomposition formula of Fe₆₀.9 Hf₁₃.5 N₂₅.6 which was annealed at 500° C.for 10.8×10³ seconds in a magnetic field of 2 kOe.

It was found that this sample exhibited an imaginary component μ" whichwas sufficiently small at frequencies below 200 MHz, and became largerthan the real component μ" around 200 MHz. The sample can besatisfactorily used at frequencies up to 200 MHz. This sample also had asaturation magnetic flux density of 1.5 T, a coercive force of 38.4 A/m(=0.48 Oe), an anisotropic magnetic field of 422.4 A/m (=5.28 Oe), amagnetostriction of 6.8×10⁻⁶, and a resistivity of 254 μΩc m, thesebeing superior magnetic properties.

It is clear from the results shown in FIGS. 17 to 22, that the softmagnetic alloy thin film according to the present invention can be usedfor magnetic devices which require large magnetostriction and highmagnetic permeability, such as magnetic surface acoustic wave devices,because the thin film has high magnetic permeability at high frequencieseven though it exhibits large magnetostriction. When the N content isset to 18.3 atomic percent or more, the imaginary component μ" can beinsignificant even at frequencies above 200 MHz, thereby minimizing thereduction of magnetic permeability.

FIGS. 23A-B show the relationship between the annealing temperature andresistivity, and the relationship between the annealing temperature andsaturation magnetic flux density, of samples having compositionalformulas of Fe₇₇.8 Hf₁₃.1 N₉.1, Fe₆₀.9 Hf₁₃.5 N₂₅.6, and Fe₆₉.5 Hf₁₂.2N₁₈.3.

It was clear from the results shown in FIGS. 23A-B that the resistivityof all the samples slightly decreased and the saturation magnetic fluxdensity slightly or substantially increased, depending on the samples,as the annealing temperature increased.

FIGS. 24A-D show the relationship between the annealing temperature andmagnetic permeability, the relationship between the annealingtemperature and magnetostriction, the relationship between the annealingtemperature and anisotropic magnetic field, and the annealingtemperature and coercive force, of samples having compositional formulasof Fe₇₇.8 Hf₁₃.1 N₉.1 and Fe₆₉.5 Hf₁₂.2 N₁₈.3.

It was found from the results shown in FIGS. 24A-D that the annealingtemperature rarely affected the magnetostriction, but significantlyaffected the magnetic permeability and anisotropic magnetic field.

FIGS 25A-D show the same relationship as that shown in FIGS. 24A-D,measured for a sample having a compositional formula of Fe₆₀.9 Hf₁₃.5N₂₅.6. The results similar to those shown in FIGS. 24A-D were obtainedfor the sample having this composition.

FIG. 26 shows X-ray diffraction patterns of samples having compositionalformulas of Fe₇₇.8 Hf₁₃.1 N₉.1 and Fe₆₉.5 Hf₁₂.2 N₁₈.3 which were usedin the measurement shown in FIGS. 24A-D and 25A-D.

Since both samples showed broad peaks unique to an amorphous phases atdiffraction angles of 40 to 60 degrees, it was determined that thesamples were mainly made up of amorphous phases.

FIGS. 27 and 28 are sketches showing a typical structure appearing in aphotograph, magnified 3.2 million times, of a sample having acompositional formula of Fe₇₇.2 Hf₁₃.2 N₁₄.6 which was annealed at 400°C. for 10.8×10³ seconds in a magnetic field of 2 kOe. In both figures,hatched areas represent crystalline structures and the unshaded areasindicate an amorphous phase. It is clear from these figures that thesoft magnetic alloy thin films according to the present invention aremainly made up of an amorphous phase in which fine-crystalline grainsare dispersed. With a scale of 6 nm indicated in the figures, it wasfound that each crystalline grain had a diameter of about 20 nm or less.

Samples having similar compositional formulas, wherein other elements Mare substituted for Hf, have similar metal structures. It is quiteexpected that these samples have superior magnetic properties atfrequencies higher than 10 MHz due to their alloy structures.

FIGS. 29 (a) and (b) illustrate a first structural example of aninductor (plane-type magnetic device) made using a magnetic film of thesoft magnetic alloy having the above-described composition.

The inductor B of this example include planar, spiral coils 2 formed onboth sides of a substrate 1, the coils 2 being coated with isolationfilms 3, the isolation films 3 being further coated with magnetic films4, and the coils 2, which are formed on both sides of the substrate 1,being electrically connected through a through hole 5 located at thecenter of the substrate 1. Terminals 6 connected to the coils 2 extendedfrom an edge surface of the inductor B.

The inductor B of this configuration exhibited inductance betweenterminals 6 by putting the plane coils 2 with the isolation films 3between the magnetic films 4.

The above-described substrate 1 was made from materials such as aceramic material, a silicon-wafer substrate, and a resin substrate. Whenthe substrate 1 is made from a ceramic material, the material may beselected from various compounds of alumina, zirconia, silicon carbide,silicon nitride, aluminum nitride, steatite, mullite, cordierite,forsterite, spinel, and others. To make the thermal expansion rate ofthe substrate close to that of silicon, it is preferable to use acompound, such as aluminum nitride, which has a large thermalconductivity and large bending strength.

The plane coils 2 were made from a conductive metal such as copper,silver, gold, aluminum, and alloys thereof. Depending on the desiredinductance, DC superposition characteristics and size, the plane coils 2can be arranged vertically or horizontally with isolation films, andelectrically connected in series. The plane coils 2 can be connected inparallel to form a transformer. Moreover, various shapes of the planecoils 2 can be made using photoeching after conductive layers are formedon the substrate. The conductive layers may be formed with anappropriate method, such as press fitting, plating, metal spray, vacuumdeposition, sputtering, ion plating, screen printing, and calcination.

The isolation films 3 were provided in order to prevent the plane coils2 from short-circuiting with the magnetic films 4 when a voltage isapplied to the plane coils 2. The isolation films 3 may preferably be aninorganic film, such as a polymer film, including a polyimide film,SiO₂, glass, and rigid carbon film. The isolation films 3 may be formedwith a method such as calcination after paste printing, hot dipping,flame spraying, vapor phase plating, vacuum deposition, sputtering, andion plating.

The magnetic films 4 comprise a film of the soft magnetic alloys whosecompositions have been described above.

The inductance of the inductor B configured as described above wasmeasured by applying an AC sine current having a frequency of severalhundred kHz and an amplitude of several mA. The measured value wasseveral hundreds of AH. Since the inductor B, configured as describedabove, is small, thin, and lightweight, and also includes the isolationfilms 4 having a superior magnetic properties, it contributes to makingplane-type magnetic devices small and lightweight, and shows largeinductance.

FIG. 30 shows a second structural example of an inductor configured witha magnetic film of the soft magnetic alloys whose compositions have beendescribed above.

In the inductor C of this example, an oxide film 11, a magnetic film 12,and an isolation film 13 were laminated on a substrate 10, in thatorder, and a plane coil 14 was formed on the isolation film 13. Theplane coil 14 and the isolation film 13 were coated with an isolationfilm 15, then a magnetic film 16 was formed on the isolation film 15.

The substrate 10 was made from a material equivalent to that used forthe substrate 1 of the previous example. The magnetic film 12 was madefrom a material equivalent to that used for the magnetic film 4 of theprevious example. The isolation film 13 was made from a materialequivalent to that used for the isolation film 3 of the previousexample.

In particular, it is preferred that the magnetic film 12 is configuredwith a magnetic film of the soft magnetic alloys having the compositionsdescribed above.

When a Si wafer substrate is used as the substrate 10, for example, theoxide film 11 can be formed by heating the Si wafer to cause thermallyoxidization. The oxide film 11 is dispensable, and can be omitted.

The inductor C configured in this example shows a high inductance, andis small and lightweight, contributing to making plane-type magneticdevices small and lightweight, in the same way as the inductor B of theprevious example.

As described above, the soft magnetic alloy thin films of the presentinvention have higher saturation magnetic flux densities than theSendust alloy and a soft magnetic amorphous alloy, and show superiorproperties of low coercive force and high magnetic permeability. Inaddition, their magnetostriction can easily be made zero with adjustmentof their compositions.

Conventional films have higher losses at higher frequencies because theimaginary component of the magnetic permeability of the conventionalfilms becomes higher than the real component at high frequencies. Thesoft magnetic alloy thin films of the present invention maintains arelatively small imaginary component of magnetic permeability at afrequency range of 30 MHz to 500 MHz, thereby enabling the thin films tobe used at high frequencies with low losses.

With use of the above-described soft magnetic alloy thin films, it ispossible to provide plane-type magnetic devices which can be used athigher frequencies.

What is claimed is:
 1. A plane-type magnetic device including a spiral,planar coil, an isolation film, and a magnetic film of a soft magneticalloy laminated on a substrate, said soft magnetic alloy comprising:afine crystalline phase with an average crystalline grain size of 10 nmin diameter or less and having a body-centered cubic structure mainlycomposed of Fe; an amorphous phase having a nitrogen (N) compound as themain composition; an element M incorporated in at least the amorphousphase, the element M consisting of at least one element selected fromthe group consisting of rare earth metal elements; and wherein saidamorphous phase comprises at least 50% of the structure of said softmagnetic alloy.
 2. A plane-type magnetic device according to claim 1,wherein said soft magnetic alloy has a composition formula of FE_(a)M_(b) N_(c), where the compositional ratios a, b, and c are atomicpercentages, wherein:

    60≦a≦80,

    7≦b≦26, and

    5≦c≦30.


3. A plane-type magnetic device according to claim 2, wherein saidcompositional ratio c is:

    10≦c≦22.


4. A plane-type magnetic device according to claim 2, wherein saidcompositional ratio c is:

    10≦c≦18.


5. A plane-type magnetic device according to claim 2, wherein saidcompositional ratio c is:

    22≦c<30.


6. A plane-type magnetic device according to claim 2, wherein saidcompositional ratio b is:

    10≦b≦15.


7. 7. A plane-type magnetic device including a spiral, planar coil, anisolation film, and a magnetic film of a soft magnetic alloy laminatedon a substrate, said soft magnetic alloy comprising:a fine crystallinephase with an average crystalline grain size of 10 nm in diameter orless and having a body-centered cubic structure mainly composed of Fe;an amorphous phase having a nitrogen (N) compound as the maincomposition; a material M incorporated in at least the amorphous phase,the material M comprising at least one element selected from the groupconsisting of rare earth metal elements; and wherein said amorphousphase comprises at least 50% of the structure of said soft magneticalloy.